内蒙古地区下垫面变化对土壤湿度数值模拟的影响

利用第二次全国土壤调查土壤质地数据（SNSS）和中国区域陆地覆盖资料（CLCV）将陆面过程模式CLM3.5（Community Land Model version 3.5）中基于联合国粮食农业组织发展的土壤质地数据（FAO）和MODIS卫星反演的陆地覆盖数据（MODIS）进行了替换，使用中国气象局陆面数据同化系统（CMA Land Data Assimilation System，CLDAS）大气强迫场资料，分别驱动基于同时改进土壤质地和陆地覆盖数据的CLM3.5（CLM-new）、基于只改进陆地覆盖数据的CLM3.5（CLM-clcv）、基于只改进土壤质地数据的CLM3.5（CLM-snss）和基于原始下垫面数据的CLM3.5（CLM-ctl），对内蒙古地区2011～2013年土壤湿度的时空变化进行模拟试验，研究下垫面改进对CLM3.5模拟土壤湿度的影响。将四组模拟结果与46个土壤水分站点观测数据进行对比分析，结果表明:相对于控制试验，CLM-clcv、CLM-snss和CLM-new都能不同程度地改进土壤湿度模拟，其中CLM-clcv主要在呼伦贝尔改进明显，CLM-snss则在除呼伦贝尔以外的大部地区改进显著，CLM-ctl模拟的土壤湿度在各层上均系统性偏大，而CLM-new模拟土壤湿度最好地反映出内蒙古地区观测的土壤湿度的时空变化特征，显著改善了土壤湿度的模拟，体现在与观测值有着更高的相关系数和更小的平均偏差与均方根误差。

Impact of Underlying Surface Change on the Numerical Simulation of Soil Moisture in Inner Mongolia of China

The Community Land Model version 3.5(CLM3.5) is used to investigate the impact of underlying surface change on soil moisture (SM) simulation over Inner Mongolia.The model is driven by CLDAS (the atmospheric forcing data of CMA Land Data Assimilation System) outputs for the period of 2011 to 2013.Four 3-year (2011-2013) experiments with different surface information,i.e.the soil texture dataset from the Second National Soil Survey on China (SNSS) and CLCV (Chinese land cover derived from vegetation map)(CLM-new),the dataset from FAO and CLCV (CLM-clcv),the dataset from SNSS and the MODIS (CLM-snss),and the dataset from FAO (Food and Agriculture Organization of United Nations) and MODIS (CLM-ctl),are conducted.Results of SM simulations from the four experiments are compared to in-situ measurements of soil moisture collected at 46 stations.It is found that the observed temporal variations of SM can be better simulated in all the three experiments (CLM-new,CLM-snss,and CLM-clcv) compared to that in the control experiment (CLM-ctl).Major improvements are found over Hulunbuir in the CLM-clcv simulation,while improvements over large areas except Hulunbuir have been found in the CLM-snss simulation.Systematic overestimation of soil moisture at each soil layer is found in the CLM-ctl simulation.Among the four experiments,the CLM-new performs best and can well reproduce the spatial-temporal patterns of soil moisture in Inner Mongolia.The high correlation coefficient between the CLM-new simulation and observations and small bias and root mean square error indicate that this experiment can well simulate soil moisture in Inner Mongolia.